Question: Emily is 4 times as old as Vanessa and is also 12 years older than Vanessa. How old is Emily?
Explanation: We can use the given information to write down two equations that describe the ages of Emily and Vanessa. Let Emily's current age be $e$ and Vanessa's current age be $v$ $e = 4v$ $e = v + 12$ Now we have two independent equations, and we can solve for our two unknowns. One way to solve for $e$ is to solve the second equation for $v$ and substitute that value into the first equation. Solving our second equation for $v$ , we get: $v = e - 12$ . Substituting this into our first equation, we get the equation: $e = 4$ $(e - 12)$ which combines the information about $e$ from both of our original equations. Simplifying the right side of this equation, we get: $e = 4e - 48$ Solving for $e$ , we get: $3 e = 48$ $e = 16$.